#ifndef __DLIST_H
#define __DLIST_H

/* This file is from Linux Kernel (include/linux/list.h)
 * and modified by simply removing hardware prefetching of list items.
 * Here by copyright, credits attributed to wherever they belong.
 * Kulesh Shanmugasundaram (kulesh [squiggly] isis.poly.edu)
 */

/*
 * Simple doubly linked list implementation.
 *
 * Some of the internal functions (“__xxx”) are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */
/**
 * container_of - cast a member of a structure out to the containing structure
 *
 * @ptr:	the pointer to the member.
 * @type:	the type of the container struct this is embedded in.
 * @member:	the name of the member within the struct.
 *
 */
#define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER)

#define container_of(ptr, type, member) ({			\
        const typeof( ((type *)0)->member ) *__mptr = (ptr);	\
        (type *)( (char *)__mptr - offsetof(type,member) ); })
/*
 * These are non-NULL pointers that will result in page faults
 * under normal circumstances, used to verify that nobody uses
 * non-initialized list entries.
 */
#define LIST_POISON1 ((void *)0x00100100)
#define LIST_POISON2 ((void *)0x00200)

struct list_head
{
	struct list_head *prev;
	struct list_head *next;
};

#define LIST_HEAD_INIT(name) {&(name), &(name)}

#define LIST_HEAD(name) \
	struct list_head name = LIST_HEAD_INIT(name)

// 宏定义语法规定只能有一条语句
// 如果需要多条语句，那就必须将多条语句放入一个do{}while(0)中使之成为一条复合语句
#define INIT_LIST_HEAD(ptr)  \
	do                       \
	{                        \
		(ptr)->next = (ptr); \
		(ptr)->prev = (ptr); \
	} while (0)

/*
 * Insert a new entry between two known consecutive entries.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_add(struct list_head *new,
							  struct list_head *prev,
							  struct list_head *next)
{
	next->prev = new;
	new->next = next;
	new->prev = prev;
	prev->next = new;
}

/**
 * list_add – add a new entry
 * @new: new entry to be added
 * @head: list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
static inline void list_add(struct list_head *new, struct list_head *head)
{
	__list_add(new, head, head->next);
}

/**
 * list_add_tail – add a new entry
 * @new: new entry to be added
 * @head: list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
static inline void list_add_tail(struct list_head *new, struct list_head *head)
{
	__list_add(new, head->prev, head);
}

/*
 * Delete a list entry by making the prev/next entries
 * point to each other.
 *
 * This is only for internal list manipulation where we know
 * the prev/next entries already!
 */
static inline void __list_del(struct list_head *prev, struct list_head *next)
{
	next->prev = prev;
	prev->next = next;
}

/**
 * list_del – deletes entry from list.
 * @entry: the element to delete from the list.
 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
 */
static inline void list_del(struct list_head *entry)
{
	__list_del(entry->prev, entry->next);
	entry->next = (void *)0;
	entry->prev = (void *)0;
}

/**
 * list_del_init – deletes entry from list and reinitialize it.
 * @entry: the element to delete from the list.
 */
static inline void list_del_init(struct list_head *entry)
{
	__list_del(entry->prev, entry->next);
	INIT_LIST_HEAD(entry);
}

/**
 * list_move – delete from one list and add as another’s head
 * @list: the entry to move
 * @head: the head that will precede our entry
 */
static inline void list_move(struct list_head *list,
							 struct list_head *head)
{
	__list_del(list->prev, list->next);
	list_add(list, head);
}

/**
 * list_move_tail – delete from one list and add as another’s tail
 * @list: the entry to move
 * @head: the head that will follow our entry
 */
static inline void list_move_tail(struct list_head *list,
								  struct list_head *head)
{
	__list_del(list->prev, list->next);
	list_add_tail(list, head);
}

/**
 * list_empty – tests whether a list is empty
 * @head: the list to test.
 */
static inline int list_empty(struct list_head *head)
{
	return head->next == head;
}

static inline void __list_splice(struct list_head *list,
								 struct list_head *head)
{
	struct list_head *first = list->next;
	struct list_head *last = list->prev;
	struct list_head *at = head->next;

	first->prev = head;
	head->next = first;

	last->next = at;
	at->prev = last;
}

/**
 * list_splice – join two lists
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 */
static inline void list_splice(struct list_head *list, struct list_head *head)
{
	if (!list_empty(list))
		__list_splice(list, head);
}

/**
 * list_splice_init – join two lists and reinitialise the emptied list.
 * @list: the new list to add.
 * @head: the place to add it in the first list.
 *
 * The list at @list is reinitialised
 */
static inline void list_splice_init(struct list_head *list,
									struct list_head *head)
{
	if (!list_empty(list))
	{
		__list_splice(list, head);
		INIT_LIST_HEAD(list);
	}
}

/**
 * list_entry – get the struct for this entry
 * @ptr:    the &struct list_head pointer.
 * @type:    the type of the struct this is embedded in.
 * @member:    the name of the list_struct within the struct.
 */
#define list_entry(ptr, type, member) \
	((type *)((char *)(ptr) - (unsigned long long)(&((type *)0)->member)))

/**
 * list_for_each    -    iterate over a list
 * @pos:    the &struct list_head to use as a loop counter.
 * @head:    the head for your list.
 */
#define list_for_each(pos, head)            \
	for (pos = (head)->next; pos != (head); \
		 pos = pos->next)
/**
 * list_for_each_prev    -    iterate over a list backwards
 * @pos:    the &struct list_head to use as a loop counter.
 * @head:    the head for your list.
 */
#define list_for_each_prev(pos, head)       \
	for (pos = (head)->prev; pos != (head); \
		 pos = pos->prev)

/**
 * list_for_each_safe    -    iterate over a list safe against removal of list entry
 * @pos:    the &struct list_head to use as a loop counter.
 * @n:        another &struct list_head to use as temporary storage
 * @head:    the head for your list.
 */
#define list_for_each_safe(pos, n, head)                   \
	for (pos = (head)->next, n = pos->next; pos != (head); \
		 pos = n, n = pos->next)

/**
 * list_for_each_entry    -    iterate over list of given type
 * @pos:    the type * to use as a loop counter.
 * @head:    the head for your list.
 * @member:    the name of the list_struct within the struct.
 */
#define list_for_each_entry(pos, head, member)                 \
	for (pos = list_entry((head)->next, typeof(*pos), member); \
		 &pos->member != (head);                               \
		 pos = list_entry(pos->member.next, typeof(*pos), member))

/**
 * list_for_each_entry_safe – iterate over list of given type safe against removal of list entry
 * @pos:    the type * to use as a loop counter.
 * @n:        another type * to use as temporary storage
 * @head:    the head for your list.
 * @member:    the name of the list_struct within the struct.
 */
#define list_for_each_entry_safe(pos, n, head, member)          \
	for (pos = list_entry((head)->next, typeof(*pos), member),  \
		n = list_entry(pos->member.next, typeof(*pos), member); \
		 &pos->member != (head);                                \
		 pos = n, n = list_entry(n->member.next, typeof(*n), member))

#endif
